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Papers by tomoya takemura
Proceedings of the Japan Academy Ser B Physical and Biological Sciences
O-Methyltransferases, which catalyze the production of small molecules in plants, play a crucial ... more O-Methyltransferases, which catalyze the production of small molecules in plants, play a crucial role in determining biosynthetic pathways in secondary metabolism because of their strict substrate specificity. Using three O-methyltransferase (OMT) cDNAs that are involved in berberine biosynthesis, we investigated the structure that was essential for this substrate specificity and the possibility of creating a chimeric enzyme with novel substrate specificity. Since each OMT has a relatively well-conserved C-terminal putative S-adenosyl-L-methionine-binding domain, we first exchanged the N-terminal halves of different OMTs. Among the 6 combinations that we tested for creating chimeric OMTs, 5 constructs produced detectable amounts of recombinant proteins, and only one of these with an N-terminal half of 6-OMT and a C-terminal half of 4′-OMT (64′-OMT) showed methylation activity with isoquinoline alkaloids as a substrate. Further enzymological analysis of 64′-OMT reaction product indicated that 64′-OMT retained the regiospecificity of 6-OMT. Further examination of the N-terminal region of 64′-OMT showed that about 90 amino acid residues in the N-terminal half were critical for reaction specificity. The creation of OMTs with novel reactivity is discussed.
Proceedings of the National Academy of Sciences
Benzylisoquinoline alkaloids, such as the analgesic compounds morphine and codeine, and the antib... more Benzylisoquinoline alkaloids, such as the analgesic compounds morphine and codeine, and the antibacterial agents berberine, palmatine, and magnoflorine, are synthesized from tyrosine in the Papaveraceae, Berberidaceae, Ranunculaceae, Magnoliaceae, and many other plant families. It is difficult to produce alkaloids on a large scale under the strict control of secondary metabolism in plants, and they are too complex for cost-effective chemical synthesis. By using a system that combines microbial and plant enzymes to produce desired benzylisoquinoline alkaloids, we synthesized (S)-reticuline, the key intermediate in benzylisoquinoline alkaloid biosynthesis, from dopamine by crude enzymes from transgenic Escherichia coli. The final yield of (S)-reticuline was 55 mg/liter within 1 h. Furthermore, we synthesized an aporphine alkaloid, magnoflorine, or a protoberberine alkaloid, scoulerine, from dopamine via reticuline by using different combination cultures of transgenic E. coli and Sacch...
Plant & cell physiology, 2010
Higher plants produce a diverse array of secondary metabolites. These chemicals are synthesized f... more Higher plants produce a diverse array of secondary metabolites. These chemicals are synthesized from simple precursors through multistep reactions. To understand how plant cells developed such a complicated metabolism, we examined the plasticity of benzyl isoquinoline alkaloid biosynthesis in transgenic Eschscholzia californica cells with the ectopic expression of Coptis japonica scoulerine-9-O-methyltransferase (CjSMT). CjSMT catalyzes the O-methylation of scoulerine to produce tetrahydrocolumbamine (THC) in berberine biosynthesis and is not involved in benzophenanthridine alkaloid biosynthesis in E. californica. While a preliminary characterization confirmed that columbamine (oxidized product of THC) was produced in transgenic E. californica cells, many newly found peaks were not identified. Here, we report the identification of novel products, including allocryptopine and 10-hydroxychelerythrine. This result indicates that CjSMT reaction products were further converted by endogen...
Higher plants produce diverse classes of metabolites. Metabolic engineering offers tremendous pot... more Higher plants produce diverse classes of metabolites. Metabolic engineering offers tremendous potential to improve the production and quality of these chemicals. This report summarizes the possibility of using metabolic engineering in benzylisoquinoline alkaloid biosynthesis. Benzylisoquinoline alkaloids, such as morphine, sanguinarine, and berberine, are synthesized from tyrosine via reticuline in Magnoliaceae, Ranunculaceae, Berberidaceae, Papaveraceae, and many other species. The early pathway from tyrosine to reticuline is common among many plant species, whereas there is more diversity in late pathways. This review describes several strategies to improve the yield and quality of benzylisoquinoline alkaloids. First, the overexpression of a rate-limiting enzyme in an early pathway to increase the overall alkaloid yield is discussed. Second, the introduction of a new branch into the pathway has been shown to produce novel metabolites. Finally, the possibility of accumulating a pathway intermediate by the knock-down of a key step is examined. Further metabolic modification is also discussed, since the latter two modifications may lead to the production of novel compound(s) from an accumulated intermediate through metabolic activation. These metabolic changes could be further modified to increase chemical diversity through somatic variation in cell culture. Besides this direct metabolic engineering with isolated biosynthetic genes, the regulation of biosynthetic activity with transcription factors and/or with reconstruction of the entire biosynthesis will also be discussed for the next generation of metabolite production.
Carapichea ipecacuanha produces various emetinetype alkaloids, known as ipecac alkaloids, which h... more Carapichea ipecacuanha produces various emetinetype alkaloids, known as ipecac alkaloids, which have long been used as expectorants, emetics, and amebicides. In this study, we isolated an O-methyltransferase cDNA from this medicinal plant. The encoded protein (CiOMT1) showed 98% sequence identity to IpeOMT2, which catalyzes the 7 0-O-methylation of 7 0-O-demethylcephaeline to form cephaeline at the penultimate step of emetine biosynthesis (Nomura and Kutchan, J. Biol. Chem., 285, 7722-7738 (2010)). Recombinant CiOMT1 showed both 7 0-O-methylation and 6 0-O-methylation activities at the last two steps of emetine biosynthesis. This indicates that small differences in amino acid residues are responsible for distinct regional methylation specificities between IpeOMT2 and CiOMT1, and that CiOMT1 might contribute to two sequential O-methylation steps from 7 0-O-demethylcephaeline to emetine.
Methods in Molecular Biology, 2010
Benzylisoquinoline alkaloids are one of the most important groups of secondary metabolites and in... more Benzylisoquinoline alkaloids are one of the most important groups of secondary metabolites and include the economically important analgesic morphine and the antimicrobial agent berberine. To improve the productivity of these alkaloids, we investigated the effects of putative rate-limiting step enzymes in alkaloid biosynthesis. We constructed several over-expression vectors for biosynthetic enzymes and introduced them into cultured California poppy, a model isoquinoline alkaloid-producing plant. HPLC/LC-MS analysis of transgenic cells revealed that these enzymes varied in their ability to increase alkaloid production. We describe the use of a rate-limiting step gene to improve alkaloid productivity.
Proceedings of the Japan Academy Ser B Physical and Biological Sciences
O-Methyltransferases, which catalyze the production of small molecules in plants, play a crucial ... more O-Methyltransferases, which catalyze the production of small molecules in plants, play a crucial role in determining biosynthetic pathways in secondary metabolism because of their strict substrate specificity. Using three O-methyltransferase (OMT) cDNAs that are involved in berberine biosynthesis, we investigated the structure that was essential for this substrate specificity and the possibility of creating a chimeric enzyme with novel substrate specificity. Since each OMT has a relatively well-conserved C-terminal putative S-adenosyl-L-methionine-binding domain, we first exchanged the N-terminal halves of different OMTs. Among the 6 combinations that we tested for creating chimeric OMTs, 5 constructs produced detectable amounts of recombinant proteins, and only one of these with an N-terminal half of 6-OMT and a C-terminal half of 4′-OMT (64′-OMT) showed methylation activity with isoquinoline alkaloids as a substrate. Further enzymological analysis of 64′-OMT reaction product indicated that 64′-OMT retained the regiospecificity of 6-OMT. Further examination of the N-terminal region of 64′-OMT showed that about 90 amino acid residues in the N-terminal half were critical for reaction specificity. The creation of OMTs with novel reactivity is discussed.
Proceedings of the National Academy of Sciences
Benzylisoquinoline alkaloids, such as the analgesic compounds morphine and codeine, and the antib... more Benzylisoquinoline alkaloids, such as the analgesic compounds morphine and codeine, and the antibacterial agents berberine, palmatine, and magnoflorine, are synthesized from tyrosine in the Papaveraceae, Berberidaceae, Ranunculaceae, Magnoliaceae, and many other plant families. It is difficult to produce alkaloids on a large scale under the strict control of secondary metabolism in plants, and they are too complex for cost-effective chemical synthesis. By using a system that combines microbial and plant enzymes to produce desired benzylisoquinoline alkaloids, we synthesized (S)-reticuline, the key intermediate in benzylisoquinoline alkaloid biosynthesis, from dopamine by crude enzymes from transgenic Escherichia coli. The final yield of (S)-reticuline was 55 mg/liter within 1 h. Furthermore, we synthesized an aporphine alkaloid, magnoflorine, or a protoberberine alkaloid, scoulerine, from dopamine via reticuline by using different combination cultures of transgenic E. coli and Sacch...
Plant & cell physiology, 2010
Higher plants produce a diverse array of secondary metabolites. These chemicals are synthesized f... more Higher plants produce a diverse array of secondary metabolites. These chemicals are synthesized from simple precursors through multistep reactions. To understand how plant cells developed such a complicated metabolism, we examined the plasticity of benzyl isoquinoline alkaloid biosynthesis in transgenic Eschscholzia californica cells with the ectopic expression of Coptis japonica scoulerine-9-O-methyltransferase (CjSMT). CjSMT catalyzes the O-methylation of scoulerine to produce tetrahydrocolumbamine (THC) in berberine biosynthesis and is not involved in benzophenanthridine alkaloid biosynthesis in E. californica. While a preliminary characterization confirmed that columbamine (oxidized product of THC) was produced in transgenic E. californica cells, many newly found peaks were not identified. Here, we report the identification of novel products, including allocryptopine and 10-hydroxychelerythrine. This result indicates that CjSMT reaction products were further converted by endogen...
Higher plants produce diverse classes of metabolites. Metabolic engineering offers tremendous pot... more Higher plants produce diverse classes of metabolites. Metabolic engineering offers tremendous potential to improve the production and quality of these chemicals. This report summarizes the possibility of using metabolic engineering in benzylisoquinoline alkaloid biosynthesis. Benzylisoquinoline alkaloids, such as morphine, sanguinarine, and berberine, are synthesized from tyrosine via reticuline in Magnoliaceae, Ranunculaceae, Berberidaceae, Papaveraceae, and many other species. The early pathway from tyrosine to reticuline is common among many plant species, whereas there is more diversity in late pathways. This review describes several strategies to improve the yield and quality of benzylisoquinoline alkaloids. First, the overexpression of a rate-limiting enzyme in an early pathway to increase the overall alkaloid yield is discussed. Second, the introduction of a new branch into the pathway has been shown to produce novel metabolites. Finally, the possibility of accumulating a pathway intermediate by the knock-down of a key step is examined. Further metabolic modification is also discussed, since the latter two modifications may lead to the production of novel compound(s) from an accumulated intermediate through metabolic activation. These metabolic changes could be further modified to increase chemical diversity through somatic variation in cell culture. Besides this direct metabolic engineering with isolated biosynthetic genes, the regulation of biosynthetic activity with transcription factors and/or with reconstruction of the entire biosynthesis will also be discussed for the next generation of metabolite production.
Carapichea ipecacuanha produces various emetinetype alkaloids, known as ipecac alkaloids, which h... more Carapichea ipecacuanha produces various emetinetype alkaloids, known as ipecac alkaloids, which have long been used as expectorants, emetics, and amebicides. In this study, we isolated an O-methyltransferase cDNA from this medicinal plant. The encoded protein (CiOMT1) showed 98% sequence identity to IpeOMT2, which catalyzes the 7 0-O-methylation of 7 0-O-demethylcephaeline to form cephaeline at the penultimate step of emetine biosynthesis (Nomura and Kutchan, J. Biol. Chem., 285, 7722-7738 (2010)). Recombinant CiOMT1 showed both 7 0-O-methylation and 6 0-O-methylation activities at the last two steps of emetine biosynthesis. This indicates that small differences in amino acid residues are responsible for distinct regional methylation specificities between IpeOMT2 and CiOMT1, and that CiOMT1 might contribute to two sequential O-methylation steps from 7 0-O-demethylcephaeline to emetine.
Methods in Molecular Biology, 2010
Benzylisoquinoline alkaloids are one of the most important groups of secondary metabolites and in... more Benzylisoquinoline alkaloids are one of the most important groups of secondary metabolites and include the economically important analgesic morphine and the antimicrobial agent berberine. To improve the productivity of these alkaloids, we investigated the effects of putative rate-limiting step enzymes in alkaloid biosynthesis. We constructed several over-expression vectors for biosynthetic enzymes and introduced them into cultured California poppy, a model isoquinoline alkaloid-producing plant. HPLC/LC-MS analysis of transgenic cells revealed that these enzymes varied in their ability to increase alkaloid production. We describe the use of a rate-limiting step gene to improve alkaloid productivity.